Francesco Berto is Professor of Logic and Metaphysics at the University of St Andrews and Research Chair at the Institute for Logic, Language and Computation (ILLC) at the University of Amsterdam. He has also worked at the Universities of Notre Dame, Aberdeen, Padua, Venice, Lugano, and at the Sorbonne-Ecole Normale Supérieure of Paris. He works on ontology, logic, epistemology, and the philosophy of computation.
Mark Jago is an Associate Professor in Philosophy at the University of Nottingham. Before that, he was a postdoctoral fellow at Macquarie University in Sydney, Australia. He mainly writes on metaphysics, logic, epistemology, and philosophy of language. His previous books are The Impossible (Oxford 2014), Reality Making (Oxford 2016, as editor), and What Truth Is (Oxford 2018).

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We need to understand the impossible. Francesco Berto and Mark Jago start by considering what the concepts of meaning, information, knowledge, belief, fiction, conditionality, and counterfactual supposition have in common. They are all concepts which divide the world up more finely than logic does. Logically equivalent sentences may carry different meanings and information and may differ in how they're believed. Fictions can be inconsistent yet meaningful. We can suppose impossible things without collapsing into total incoherence. Yet for the leading philosophical theories of meaning, these phenomena are an unfathomable mystery. To understand these concepts, we need a metaphysical, logical, and conceptual grasp of situations that could not possibly exist: Impossible Worlds. This book discusses the metaphysics of impossible worlds and applies the concept to a range of central topics and open issues in logic, semantics, and philosophy. It considers problems in the logic of knowledge, the meaning of alternative logics, models of imagination and mental simulation, the theory of information, truth in fiction, the meaning of conditional statements, and reasoning about the impossible. In all these cases, impossible worlds have an essential role to play.